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FARMERS  BULLETIN  - 1 1 67 

UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 


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rpHIS  BULLETIN  is  written  in  simple  language  for 
-*-  the  man  who  breeds  farm  animals,  who  wants  to 
learn  the  rudiments  of  the  science  of  breeding,  and 
how  to  apply  them  in  practice.  It  sets  forth  some 
of  the  known  facts  regarding  the  operation  of 
the  forces  of  heredity.  Controversial  subjects  are 
avoided  so  far  as  possible. 

The  reader  who  cares  to  go  deeper  into  the  study 
of  genetics  is  referred  to  textbooks  on  the  subject, 
and  particularly  to  Department  Bulletin  No.  905, 
"  Principles  of  Livestock  Breeding,"  by  Sewall 
Wright.  It  is  published  by  the  U.  S.  Department 
of  Agriculture,  and  is  obtainable  from  the  Superin- 
tendent of  Documents,  Government  Printing  Office, 
Washington,  D.  G.,  for  15  cents. 

Contribution  from  the  Bureau  of  Animal  Industry 

JOHN  R.  MOHLER,  Chief 
Washington,  D.  C.  November,  1920 


ESSENTIALS  OF  ANIMAL  BREEDING. 


GEORGE  M.  ROMMEL, 
Chief,  Animal  Husbandry  Division, 


CONTENTS. 


Basic  facts  about  heredity 

The  science  of  breeding 

The  unit  of  life 

The  beginnings  of  life 

The  gestation  period 

Incubation  period  in  birds. 

Determination  of  sex 

Fecundity 

Prepotency — Mendel's  law. 

The  art  of  breeding 

Selection 

Inbreeding 


Page. 
3 
4 
4 
5 
8 

10 
10 
10 
11 
17 
17 
20 


The  art  of  breeding — Continued. 

Outcrossing 

Pure  breeding 

The  value  of  a  pedigree 

Livestock  improvement 

Grading  up 

Crossbreeding 

Some  incorrect  ideas  of  heredity 

Telegony 

Maternal  impressions 

Conclusions... 


Page. 

24 
24 
26 
31 
31 
32 
33 
33 
35 
36 


BASIC  FACTS  ABOUT  HEREDITY. 

IN  DEALING  with  the  subject  of  heredity  we  must  recognize 
clearly  the  following  facts:  First,  animal  and  plant  forms,  as  a 
rule,  have  developed  gradually  and  very  slowly,  by  very  small 
changes ;  in  short,  by  the  process  known  as  evolution.  Second,  what- 
ever an  animal  has,  so  far  as  its  inheritance  is  concerned,  it  gets  from 
its  parents — they  get  theirs  from  their  parents,  and  so  on  clear  back 
to  the  beginning;  nothing  was  imposed  from  the  outside.  For  the 
present,  accept  this  fact  without  question.  We  shall  try  to  make  it 
clear  later.  Third,  a  very  clear  distinction  should  be  drawn  between 
the  effects  of  inheritance  and  the  effects  of  food  and  environment. 

Every  one  who  is  at  all  familiar  with  domestic  animals  knows  what 
a  wonderful  effect  the  food  an  animal  eats  has  on  its  development, 
especially  when  it  is  young.  It  is  also  known  that  the  younger  an 
animal  is  the  more  readily  it  is  influenced  by  its  food.  Now,  from  the 
very  first  moment  that  a  young  animal  begins  to  develop,  from  the 
very  instant  that  growth  begins  with  the  fertilization  of  the  egg 
cell,  it  receives  food  from  some  source  or  it  dies.  When  it  is 
only  a  single  cell  it  is  being  fed.  If  a  young  animal  after  birth  is 

NOTE. — In  the  preparation  of  this  article,  the  writer  received  material  assistance 
from  officers  of  the  Bureau  of  Animal  Industry,  especially  Messrs.  F.  R.  Marshall  (now 
secretary  of  the  National  Wool  Growers'  Association),  Sewall  Wright,  'Dr.  John  E. 
Mohler,  and  Mr.  D.  S.  Burch.  He  is  also  greatly  indebted  to  Mr.  Dewitt  C.  Wing,  of 
Chicago,  who  made  many  helpful  suggestions. 


435054 


3 


4  »::»*.  Farmers'  Bulletin  1167. 

easily  influenced;  by  its  food,  how  much  more  will  the  delicate  little 
creature,  known  as- the  fetus'or' Embryo,  be  influenced  by  the  character 
of  its  food  supply.  A  clear  recognition  of  this  fact  will  explain  many 
occurrences  which  are  often  attributed  to  supernatural  influences, 
and,  at  the  same  time,  the  breeder  who  recognizes  this  fact  will  not 
neglect  proper  attention  to  the  nourishment  and  care  of  the  pregnant 
mother  as  well  as  the  nursing  animal. 

Accidents  and  disease  also  are  important  in  their  effects  on  the 
growing  embryo.  If  an  incubator  is  neglected  on  a  cold  night  and 
the  eggs  become  chilled,  the  hatch  is  seriously  impaired  and  a  large 
number  of  chicks  are  killed  in  the  shell.  If  an  in-foal  mare  is  sub- 
jected to  very  heavy  strains  or  forced  to  pull  extremely  heavy  loads, 
the  foal  may  be  born  too  soon  or  even  be  killed  in  the  womb.  Con- 
tagious abortion  may  get  into  the  herd  without  the  owner's  knowing 
it  and  cause  the  loss  of  a  large  proportion  of  calves.  Heredity,  how- 
ever, has  nothing  whatever  to  do  with  any  of  these  things. 

THE  SCIENCE  OF  BREEDING. 

THE  UNIT  OF  LIFE. 

The  smallest  unit  of  life  is  the  cell.  A  single  cell  is  very  small, 
usually  of  microscopic  size.  It  is  surrounded  by  a  membrane,  and 
each  cell  usually  contains  a  nucleus — a  sort  of  center  of  the  things 
that  go  on  in  the  cell.  The  animal  body  contains  millions  of  cells, 
but  those  in  which  we  are  most  interested  at  this  moment  are  the 
cells  from  the  union  of  which  a  new  animal  life  begins.  They  are 
the  germ  cells.  They  contain  the  hereditary  material  which  de- 
termines the  identity  of  each  individual  and  which  is  known  as  the 
germ  plasm.  This  is  the  bit  of  life  which  passes  down  the  line  of 
descent  with  each  succeeding  generation.  It  appears  in  the  mother 
in  the  egg  cell,  and  in  the  father  in  the  sperm  cells.  This  material 
is  composed  of  elements  which  seem  to  be  handed  on  unchanged 
from  generation  to  generation.  Only  a  portion  of  the  elements  in 
the  germ  plasm  of  the  parent  goes  into  each  egg  or  sperm,  however, 
as  is  explained  in  more  detail  later.  The  element  of  chance  enters  to 
such  an  extent  in  determining  which  elements  shall  go  into  a  par- 
ticular germ  cell  that  there  may  be  a  marked  dissimilarity  among 
individuals  which  are  members  of  the  same  family.  Even  more  im- 
portant than  the  influence  of  food  on  the  developing  embryo  and  the 
young,  growing  animal  is  the  operation  of  chance  in  determining 
the  identity  of  the  new  life. 

The  cells  from  which  all  life  starts  are  developed  in  the  genera- 
tive organs.  The  egg  (the  female  cell)  is  developed  in  the  ovary 
of  the  female;  the  sperm  (the  male  cell)  is  developed  in  the  testicle 
of  the  male.  In  mammals  each  female  has  two  ovaries,  one  on 


Essentials  of  Animal  Breeding.  5 

each  side,  situated  in  the  abdominal  cavity.  Connecting  the  ovaries 
with  the  uterus  are  the  Fallopian  tubes.  The  uterus  is  the  womb, 
the  chamber  in  which  the  young  fetus  develops  until  it  is  ready  for 
birth.  The  uterus  connects  with  the  vagina,  through  which  the 
sperm  is  introduced  into  the  uterus  and  down  which  the  young  ani- 
mal passes  at  birth.  The  genital  organs  and  the  urinary  organs 
have  the  same  outlets  from  the  body. 

When  an  egg  matures  in  the  ovary  it  passes  down  the  Fallopian 
tubes  into  the  uterus.  If  no  sperm  is  introduced,  the  egg  is  thrown 
off  infertile.  In  female  animals  an  egg  matures  at  fairly  regular 
intervals,  and  this  corresponds  with  some  exactness  to  what  is  known 
as  the  period  of  heat  or  oestrum. 

The  period  of  heat  varies  considerably  in  different  species  and 
in  different  breeds  and  individuals  of  the  same  species.  It  usually 
occurs  at  intervals  of  about  three  weeks.  In  mares  it  appears  on 
the  ninth  day  after  foaling,  lasting  two  or  three  days.  In  cows  it 
appears  in  from  three  to  four  weeks  after  calving  when  the  cow  is 
not  suckling  a  calf,  and  in  from  six  to  eight  weeks  if  she  is.  The 
heat  period  lasts  only  about  one  day  in  cows.  Sows  come  in  heat 
three  days  after  farrowing,  and  not  again  until  a  week  after  the 
pigs  are  weaned.  In  sheep,  except  for  a  few  breeds,  such  as  the 
Dorset,  ewes  in  North  America  ordinarily  come  in  heat  only  in  the 
fall  for  a  number  of  periods  of  two  or  three  days  each  at  intervals 
of  from  two  to  three  weeks. 

Females  usually  accept  service  only  during  the  period  of  heat.  It 
seems  to  make  little  difference  when  service  is  made,  whether  early  or 
late  in  heat.  As  a  rule,  not  more  than  one  service  is  necessary  dur- 
ing one  period  of  heat  to  insure  conception.  After  conception  takes 
place,  the  female  does  not  generally  come  in  heat  again  during  preg- 
nancy. 

Male  cells,  or  spermatozoa,  are  carried  in  the  seminal  fluid.  There 
is  only  one  egg,  as  a  rule,  except  in  such  animals  as  hogs,  rats,  and 
others,  which  usually  have  several  young  at  a  birth.  There  are,  how- 
ever, millions  of  sperm  cells,  but  only  one  of  them  is  needed  or  used  to 
fertilize  one  egg.  Let  us  now  proceed  to  a  consideration  of  the  first 
step  in  the  formation  of  the  new  life. 

THE   BEGINNINGS    OF   LIFE. 

The  life  which  results  when  two  animals  are  mated  has  its  con- 
trolling elements  in  the  nuclei  of  the  germ  cells.  These  nuclei  con- 
tain a  substance  called  chromatin,  represented  by  very  minute  bodies 
called  chromosomes.  Chromatin  and  chromosomes  are  found  in  all 
cells  all  over  the  body,  and  the  number  of  chromosomes  in  each  cell 
is  the  same  for  each  species  of  animal.  Except  for  the  accessory 


6  Farmers'  Bulletin  1167. 

chromosome  (which  determines  sex),  they  are  always  in  pairs.1  In 
many  of  the  domestic  animals  and  in  man  the  number  of  chromo- 
somes is  between  40  and  48,  depending  on  the  species.  Just  why  this 
number  should  be  limited  and  invariable  we  do  not  know.  It  is  no 
more  remarkable,  however,  that  each  cell  in  the  hog's  body,  for  ex- 
ample, should  have  40  chromosomes  (which  is  the  case)  than  that  each 
normal  hog  should  have  four  legs. 

This  is  easily  understood  until  we  come  to  explain  what  happens 
when  the  egg  cell  is  fertilized  at  conception.  Obviously  an  egg 
with  40  chromosomes  and  a  sperm  cell  with  40  chromosomes  could 
not  unite,  because  that  would  result  in  a  cell  with  80  chromosomes  and 
only  40  is  the  rule.  It  just  wouldn't  work,  any  more  than  a  pig 
with  eight  legs  would  work.  Therefore,  to  prevent  the  doubling  of 
the  number  of  chromosomes  at  conception,  nature  puts  the  germ 
cells,  both  male  and  female,  through  a  maturing  process  known  as 
maturation,  so  that,  just  before  the  two  unite,  each  has  only  half 
the  normal  number  of  chromosomes  for  the  species,  one  from  each 
of  the  pairs  present  before  maturation.2  When  the  two  cells  unite, 
therefore,  the  fertilized  egg  has  the  usual  number  of  chromosomes' 
carried  by  the  cells  of  the  species.  This  process  occurs  only  in  the 
case  of  reproductive  cells. 

When  two  animals  are  mated,  what  happens?  The  reproductive 
cells  have  gone  through  the  maturing  process  and  are  now  ready 
for  union.  The  sperm  cells  are  active  and  move  around  until  they 
come  into  contact  with  the  egg.  Several  may  surround  the  egg,  but 
only  one  unites  with  it.  The  membrane  surrounding  the  egg  cell  is 
pierced  by  the  head  of  a  sperm  cell.  The  two  become  one  and  the 
egg  is  now  fertile.  It  needs  only  nourishment  to  become  in  time  a 
full-fledged  baby  member  of  its  race. 

Food,  of  course,  will  have  a  profound  influence  on  this  little 
mite  of  life,  but,  so  far  as  we  know,  the  character  of  the  resulting 
animal,  its  sex,  its  identity,  and  its  individuality,  whether  it  is  to 
be  white  or  black,  long-haired  or  short-haired,  ring-streaked  or 
spotted,  are  now  settled  by  the  laws  of  life.  This  minute  cell  now  car- 
ries in  itself  all  the  force  of  inheritance  from  all  the  ancestors  behind 
it  to  the  beginning  of  life  on  earth.  Every  champion  you  or  I  have 
known  began  his  career  in  just  this  way.  Many,  many  influences 
stepped  in  and  had  an  effect  on  his  subsequent  development.  Some  of 
these  are  easy  to  determine,  but  others  are  so  obscure  that  theories 
and  fancies  have  grown  up  to  explain  them. 

What  value  has  this  information  for  the  practical  breeder?  Can 
he  use  it  in  making  his  methods  more  efficient?  He  can  not  use  it 

1  For  a  discussion  of  the  accessory  or  X-Chromosome,  the  reader  is  referred  to  textbooks. 

2  Biologists  call  this  process  spermato genesis  in  the  case  of  the  male  germ   cells  and 
oogenesis  in  the  case  of  the  female  germ  cells. 


Essentials  of  Animal  Breeding.  7 

directly,  but  indirectly  it  can  be  most  valuable  to  him,  because  it 
explains  many  things  that  otherwise  are  difficult  to  understand. 

Suppose  we  are  breeding  animals  in  which  the  number  of  chromo- 
somes is  only  four  (two  pairs).  By  the  time  both  egg  and  sperm 
cells  had  gone  through  the  maturing  process,  and  the  egg  had  been 
fertilized,  16  different  combinations  would  be  possible,  some  of  them 


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A 


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'  • 


What  Chromosomes  Look  Like. 
(Courtesy  of  Dr.  E.  E.  Carothers.) 

FIG.  1. — A  remarkable  photograph  of  a  group  of  maturing  male  germ  cells  taken 
through  a  high-power  microscope.  The  pairs  of  darkly  stained  chromosomes  may 
easily  be  seen  in  two  of  the  cells  in  the  act  of  separating  to  form  the  nuclei  of  two 
new  cells.  Each  of  these  resulting  cells  will  have  only  half  the  original  number  of 
chromosomes  and  will  thus  be  ready  for  union  with  a  similarly  reduced  egg  cell. 
Hereditary  characteristics  are  transmitted  in  the  chromosomes. 

The  factors  which  make  up  the  identity  of  the  chromosomes  bear  very  much  the 
same  relation  to  heredity  that  atoms  bear  to  chemistry. 

no  doubt  differing  very  little  from  each  other,  but  others  having 
little  mutual  resemblance.  In  animals  such  as  hogs,  however,  with 
20  pairs  of  chromosomes  in  each  cell,  the  possible  combinations  are 
almost  infinite  in  number.3 

These  combinations  are  the  results  of  chance.  Here  we  have  an 
egg  with  20  pairs  of  chromosomes,  about  to  mature.  Twenty  of 
these  chromosomes  only  will  be  left  when  the  egg  is  ready  to  unite 

8  The  number  of  possible  combinations  in  this  particular  case  is  1,099,511,627,776. 


8  Farmers'  Bulletin  1167. 

with  the  sperm  cell.  What  20  will  it  be?  Chance  alone  can  tell, 
except  that  there  will  be  one  from  each  pair.  Here  comes  the  sperm 
cell,  to  mature  which  a  similar  process  was  gone  through.  Chance 
again  determined  that  20  out  of  the  original  40  "chromosomes  should 
disappear  and  no  determination  can  be  made  to  show  which  20 
would  prevail.  But  this  is  not  all.  The  sperm  cell  does  not  come 
alone.  It  .comes  in  swarms,  but  only  one  sperm  cell  penetrates  the 
cell  membrane  and  fertilizes  the  egg.  What  determines  which  of 
the  thousands  of  sperm  cells  will  be  the  one?  Chance  again. 

The  chromatin  is  the  chief,  if  not  the  sole,  determining  factor  in 
the  development  of  the  identity  of  the  new  individual,  and  the 
chromosomes  are  the  agents  by  which  this  identifying  process  is 
carried  out.  When  we  think  of  the  great  number  of  combinations 
of  chromosomes  possible  before  fertilization  is  actually  effected,  we 
begin  to  understand  why  it  is  that  members  of  the  same  family 
often  do  not  look  alike  and  why  we  have  so  many  disappointments 
in  breeding  animals. 

If  chance  is  the  sole  factor  in  determining  what  chromosomes  shall 
persist,  where  does  intelligent  breeding  come  in?  Of  what  advan- 
tage is  it  to  exercise  care  in  matings?  Why  not  leave  it  all  to 
chance  ? 

The  simple  answer  to  these  questions  is  that  we  can  lessen  the 
probability  of  undesirable  working  of  the  laws  of  chance  by  increas- 
ing the  uniformity  of  the  chromosomes.  That  is  done  by  careful 
selection  to  a  certain  type  and  by  working  with  a  group  of  animals 
whose  ancestry  is  known.  The  highest  examples  of  such  methods 
are  found  in  the  work  of  breeders  of  purebred  livestock  where  un- 
broken and  known  lines  of  descent  run  back  for  a  great  many  genera- 
tions, sometimes  for  50  years  or  more  on  a  single  farm  under  the 
ownership  of  a  single  human  family.  The  discussion  of  the  subject 
of  selection  will  be  found  under  that  heading  later. 

THE  GESTATION   PERIOD. 

From  the  time  the  egg  is  fertilized,  developments  are  rapid.  The 
fertilized  egg  divides  and  subdivides  with  multitudes  of  subdivisions, 
until  in  time  the  embryo  "  begins  to  look  like  something,"  and  we 
can  make  out  the  form  of  the  animal  and  its  parts.  The  time  be- 
tween the  fertilization  of  the  egg  and  the  birth  of  the  young  animal 
is  known  as  the  period  of  gestation.  This  period  varies  with  the 
kind  of  animal.  The  period  for  the  common  domestic  animals  is 
shown  below,  followed  by  a  table  to  determine  how  long  a  time  may 
be  expected  to  elapse  between  service  and  birth.  To  make  a  practical 
application  of  the  table  count  forward  the  correct  number  of  days 
from  the  date  of  service. 


Essentials  of  Animal  Breeding. 


9 


Gestation  period  of  various  animals. 

Mare 11  months  (340  days). 

Jennet 12  months  (365  days). 

Cow 9i  months  (280  days). 

Ewe 5  months  (150  days). 

Goat 5  months  (150  days). 

Sow 4  months  (114  days). 

Probable  date  of  birth  of  young,  female  bred  on  first  day  of  the  month   (Sewall 

Wright). 


Probable  date  of  birth. 

Date  of 

service. 

Sow. 

Ewe. 

Cow. 

Mare. 

Jan.     1 
Feb.    1 

Apr.    25 
May    26 

May    31 
July      1 

Oct.     7 
Nov.   8 

Dec.    7 
Jan.     7 

Mar.    1 

June   23 

July    29 

Dec.    6 

Feb.    4 

Apr.     1 

July    24 

Aug.    29 

Jan.     6 

Mar.    7 

May     1 

Aug.    23 

Sept.  28 

Feb.    5 

Apr.    6 

June    1 

Sept.  23 

Oct.    29 

Mar.    8 

May    7 

July    1 

Oct.    23 

Nov.   28 

Apr.    7 

June   6 

Aug.    1 

Nov.   23 

Dec.    29 

May    8 

July    7 

Sept.  1 

Dec.    24 

Jan.     29 

June   8 

Aug.    7 

Oct.     1 

Jan.     23 

Feb.    28 

July     8 

Sept.  6 

Nov.    1 

Feb.    23 

Mar.    31 

Aug.    8 

Oct.    7 

Dec.    1 

Mar.    25 

Apr.    30 

Sept.  7 

Nov.   6 

Variations  in  the  period  of  gestation  for  animals  of  the  same  kind 
are  not  readily  explained.  Some  animals,  such  as  sows,  are  quite 
uniform  in  the  length  of  the  gestation  period.  In  mares  there  is  a 
considerable  variation.  It  has  been  suggested  that  in  mares  some 
time  may  elapse  between  the  moment  of  service  and  the  actual  fer- 
tilization of  the  egg  by  the  sperm  cell.  In  guinea  pigs  the  size  of 
the  litter  affects  the  period  of  gestation,  the  period  being  shorter  for 
a  large  litter  than  for  a  small  one.  The  health  of  the  mother  during 
pregnancy  also  has  an  effect. 

During  the  gestation  period  the  young  animal  is  carried  in  the 
mother's  womb  and  is  not  connected  directly  with  her  body.  The 
blood  vessels  and  nerves  of  the  mother  do  not  connect  with  those  of 
the  growing  embryo,  but  from  the  start  the  little  one  has  its  own 
little  system  of  circulation  and  its  own  nervous  system.  It  is  carried 
in  an  enveloping  sac  which  is  attached  to  the  wall  of  the  mother's 
womb  by  buttons  (cotyledons)  which  become  detached  when  the  time 
comes.  The,  young  are  nourished  by  blood  passing  from  the  mother's 
body  through  the  walls  of  the  uterus  into  the  sac  in  which  the  fetus 
is  carried,  and  thence  into  the  body  of  the  young  animal  by  trans- 
fusion, much  as  water  would  pass  into  a  paper  sack  if  you  should 
lower  it  into  a  bucket  of  water. 
3985°— 20 2 


10  Farmers'  Bulletin  H67. 

INCUBATION   PERIOD   IN   BIRDS. 

In  birds  the  incubation  period  corresponds  to  the  gestation  period 
in  mammals.  The  period  which  elapses  from  the  time  eggs  are  put 
on  to  hatch  until  the  chicks  emerge  is  shown  below.  Young  birds  are 
nourished  in  the  embryonic  stages  of  their  development  by  absorbing 
from  the  yolk  the  nutriment  needed. 

Incubation  period  of  various  birds. 

Days. 

Goose 30 

Duck 28 

Turkey —  28 

Guinea  fowl 25 

Chicken 21 

Pigeon 17 

Much  may  be  learned  by  any  one  of  a  studious  nature  by  careful 
observations  of  the  deArelopment  of  the  embryo  of  chickens.  The 
germinal  disk  may  be  plainly  seen  even  in  a  fresh-laid  egg,  which, 
whether  fertile  or  not,  looks  the  same  to  the  naked  eye.  When  put 
into  an  incubator,  however,  the  fertile  egg  begins  to  develop  rapidly, 
and  the  transformation  in  the  brief  period  of  three  weeks  is  won- 
derful. The  course  of  this  development  in  fertile  eggs  can  be  dis- 
tinguished easily  from  day  to  day  by  the  familiar  process  of  candling 
eggs,  or  it  can  be  studied  in  detail  by  carefully  breaking  the  eggs 
into  a  saucer. 

DETERMINATION  OF  SEX. 

As  the  growth  of  the  embryo  progresses,  sex  becomes  apparent. 
Sex  seems  to  be  determined  by  one  of  the  chromosomes,  and  is  prob- 
ably settled  at  the  time  of  conception.4  The  determination  of  sex 
is  therefore  a  matter  of  chance  over  which  the  breeder  probably  has 
no  control.  For  practical  purposes,  the  breeder  will  find  that,  over 
a  period  of  years,  he  gets  nearly  equal  numbers  of  both  sexes. 

FECUNDITY. 

The  subject  of  fecundity  is  of  great  practical  importance  to 
breeders  of  animals.  Fecundity  ^depends  very  largely  on  the  number 
of  eggs  which  are  matured  at  a  given  time  by  the  female.  Animals 
in  which  multiple  births  are  the  rule  (of  which  sows  are  a  common 
example)  not  only  mature  a  considerable  number  of  egg  cells  at 
one  period  of  heat,  but  each  one.  is  fertilized  by  a  separate  sperm 
cell.  In  some  cases,  howrever,  the  fertilized  egg  may  divide  and 
twins  or  a  larger  number  of  young  result.  Such  twins  are  known 
as  identical  twins,  and  are  usually  of  the  same  sex,  with  very  strong 

*See  note  (2)  page  6. 


Essentials  of  Animal  Breeding.  H 

points  of  similarity.  Young  from  multiple  births,  resulting  from 
the  fertilization  of  different  egg  cells,  show  as  wide  a  difference 
in  individual  characteristics  as  young  resulting  from  separate  births. 
The  most  prolific  of  the  common  domestic  animals  are  the  birds. 
The  domestic  hen  may  lay  more  than  200  eggs  in  a  single  year. 

The  common  practice  of  British  shepherds,  known  as  "flushing" 
ewes,  has  been  claimed  to  increase  the  proportion  of  lambs  in  the 
flock.  This  practice  consists  in  giving  the  ewes  an  increase  in  their 
feed,  both  grain  and  succulent  pasture,  so  that  they  are  gaining  in 
weight  and  condition  at  breeding  time.  No  exact  scientific  data 
have  been  available  until  recently,  when  Marshall  and  Potts,  of  the 
Bureau  of  Animal  Industry,  conducted  experiments  which  confirmed 
the  correctness  of  the  British  practice.  They  also  have  evidence 
which  indicates  that  the  success  of  the  practice  depends  on  cutting 
off  the  grain  ration  and  putting  the  ewes  on  short  pasture  as  soon 
as  thev  are  bred. 


-      .        r,  -••:;-:•.••/- 

L. 


What  a  Good  Mother  Can  Do. 

FIG.  2. — The  ewe  at  the  right  was  lambed  in  March,  1914.  She  was  a  prize  winner  as  a 
yearling  and  as  a  two-year-old.  Her  first  lamb  was  a  ram  dropped  in  1916.  Since 
then  she  has  had  seven  lambs.  The  other  two  ewes  are  her  twins  of  1919  and  were 
shown  in  the  trio  for  Hampshire  ewe  lambs,  winning  first  prize  at  the  1919  Inter- 
national Live  Stock  Exposition.  The  lamb  at  her  side  is  her  1920  contribution  to 
the  wealth  of  America's  purebred  livestock  industry. 

The  rules  or  laws  of  the  inheritance  of  fecundity  are  not  all  known, 
but  to  some  extent  it  is  dependent  on  inheritance  from  the  mother; 
therefore,  the  selection  of  females  which  have  a  tendency  to  produce 
a  large  number  of  young  at  a  birth  will  tend  to  increase  the  returns 
from  the  flock  or  herd.  This  is  of  practical  importance  in  the  case 
of  hogs,  sheep,  goats,  and  poultry.  Twins  in  cattle  are  objectionable 
unless  of  the  same  sex.  When  a  heifer  is  a  twin  with  a  bull  calf, 
the  heifer  is  known  as  a  "  freemartin  "  and  in  the  majority  of  in- 
stances is  sterile. 

PREPOTENCY— MENDEL'S   LAW. 

Prepotency  is  the  power  of  an  animal,  male  or  female,  to  stamp  its 
characteristics  on  its  offspring.  If  this  ability  is  handed  on  to  sons 


12 


Farmers'  Bulletin  1167. 


and  daughters,  we  say  that  the  stock  "  breeds  on."  In  rare  instances 
an  animal,  usually  a  male,  is  found,  which  has  such  power  as  a  breeder 
that  it  leaves  an  indelible  impress,  even  to  the  extent  of  becoming  the 
fountain  head  of  a  new  breed,  such  as  the  stallions  Justin  Morgan, 
Hambletonian  10,  and  Denmark. 

Most  of  the  cases  of  prepotency  which  the  breeder  usually  meets 
with  are  probably  instances  of  the  operation  of  what  is  called 
Mendel's  law.  A  clear  explanation  of  this  great  law  of  heredity  can 
not  be  made  within  the  scope  of  this  short  article,  and  the  interested 
reader,  if  he  cares  to  go  into  the  subject  in  detail,  is  referred  to  Dr. 
Wright's  bulletin.5 


How  Good  Blood  "  Breeds  on." 

FIG.  3. — Cannon,  Standardbred  stallion  at  head  of  United  States  Government  stud, 
Buffalo,  Wyo.,  a  horse  which  has  been  remarkably  successful  in  stamping  his 
characteristics  on  his  offspring.  Photograph  taken  when  Carmon  was  20  years  old. 

It  must  be  pointed  out,  however,  that  most  operations  of  heredity 
are  not  simple;  on  the  contrary,  they  are  highly  complex  and  often 
extremely  difficult  to  understand.  The  chief  use  which  the  practical 
breeder  of  domestic  animals  can  make  of  Mendel's  law  at  this  time 
is  to  find  in  it  an  explanation  of  occurrences  that  otherwise  have  no 
rational  explanation. 

One  of  the  most  interesting  applications  of  Mendel's  law  in  cattle 
breeding  is  the  inheritance  of  the  polled  characteristic.  If  we  breed 
a  horned  cow  to  a  Red  Polled,  Galloway,  Angus,  or  other  true  polled 
bull,  the  chances  are  9  to  1  or  better  that  we  shall  get  a  polled  calf. 
The  white  face  of  the  Hereford  appears  to  be  a  similar  instance. 

5  TJ.   S.  Department  of  Agriculture  Bulletin  905,   "Principles  of  Livestock  Breeding." 


Essentials  of  Animal  Breeding. 


13 


How  Good  Blood  "  Breeds  on." 

FIG.  4. — Albion,  one  of  Carmon's  first  sons  used  in  the  Government  stud  as  a  sire. 
Note  the  remarkable  resemblance  between  this  horse  and  Carmon.  Photograph  was 
taken  when  Albion  was  nine  years  old. 


i 


How  Good  Blood  "  Breeds  on.' 


FIG    5. — Defender,  son  of  Albion.     Photograph  taken  when  Defender  was   six  years 
old.    Note  that  the  type  has  been  handed  down  from  grandfather  to  grandson. 


14 


Farmers'  Bulletin  1167. 


If  we  breed  a  common  cow  to  a  Hereford  bull,  we  get  a  calf  with  a 
white  face.  We  say,  therefore,  that  polled  breeds  are  very  prepotent 
so  far  as  "  taking  the  horns  off  "  is  concerned,  and  that  the  Hereford 
is  prepotent  in  putting  a  white  face  on  his  calves.  This  may  happen 
either  way ;  that  is,  polled  bull  and  horned  cow,  or  horned  bull  and 
polled  cow,  Hereford  bull  and  plain-faced  cow,  or  plain-faced  bull 
and  Hereford  cow.  The  temptation  is  to  make  great  claims  for  the 
prepotency  of  the  breed  as  a  whole  on  the  evidence  of  one  or  two 
points  only.  For  see  what  happens  when  we  mate  a  Hereford  with 
one  of  the  polled  breeds.  Then  we  get  a  polled,  white- faced  calf. 


How  Bad  Blood  "  Breeds  on." 

FIG.  6. — A  spotted  stallion  of  nondescript  breeding  used  extensively  as  a  sire  in  the 
community  where  he  was  owned.  Note  not  only  the  bad  color,  which  is  almost 
unmarketable,  but  also  the  curby  hocks  and  generally  mean  appearance. 

These  points  are  not  prepotency  at  all,  but  manifestations  of  Men- 
delian  "  dominance."  The  polled  character  is  dominant  over  the 
recessive  horned  character,  and  the  white  face  over  the  recessive  plain 
face;  but  these  cases  do  not  necessarily  indicate  that  the  animal  is 
particularly  prepotent  in  other  characters  of  much  more  practical 
importance.  The  same  rule  seems  to  apply  in  the  inheritance  of  the 
black  color  in  sheep,  black  acting  apparently  as  a  recessive  to  the 
usual  white  color.  It  can  readily  be  eliminated  by  culling  out  the 
black  lambs. 

A  great  many  data  have  been  accumulated  as  to  the  characters 
in  animals  which  illustrate  the   operation   of  Mendel's   law,   but 


Essentials  of  Animal  Breeding. 


How  Bad  Blood  "  Breeds  on." 

FIG.  7. — A  daughter  of  the  spotted  stallion.     Observe  crooked  hind  legs,  as  well  as 

bad  color. 


How  Bad  Blood  "  Breeds  on." 

FIG  8. — Another  daughter  of  the  same  stallion.  Note  how  the  curby  hocks  have  been 
transmitted  and  how  there  is  also  a  striking  tendency  for  the  spotted  color  to 
prevail.  Some  of  the  stallion's  bad  qualities  appear  in  the  forelegs  on  this 
individual. 


16  Farmers'  Bulletin  1167. 

apart  from  the  horns  of  cattle,  coat  color,  eye  color,  and  the  like, 
the  application  of  this  law  to  livestock  breeding  has  a  long  way 
to  go  before  its  principles  are  adaptable  to  practical  use  by  breeders. 
It  is  fairly  certain,  however,  that  many  of  the  obscure  happenings 
in  animal  breeding  are  really  manifestations  of  Mendelism.  Most 
cases  of  atavism  ("throw  backs"  to  a  remote  ancestor),  for  ex- 
ample, are  probably  Mendelism  in  practice. 

The  animal  structure  is  so  diverse  and  complicated  that  the  de- 
termination of  the  application  of  Mendel's  law  to  the  inheritance 
of  the  characters  which  affect  the  commercial  value  of  domestic 
animals  is  a  task  of  tremendous  magnitude.  Great  progress  has  been 
made  in  laying  the  foundations  for  the  scientific  study  of  animal 
breeding  by  working  out  the  principles  of  this  law,  and  we  may  ex- 
pect still  greater  progress  in  the  future.  Biologists  who  are  studying 
heredity  have  their  faces  set  in  the  right  direction.  The  accomplish- 


FIG.  9. — Purebred  Hereford  sire,  scrub  dam,  and  offspring.     Note  how  the  character- 
istic markings  of  the  Hereford  sire,  especially  the  white  face,  are  transmitted. 

ments  of  the  last  twenty  years  in  the  study  of  heredity  have  taken  this 
subject  out  of  the  field  of  guesswork,  and  for  this  service  all  animal 
breeders  are  under  obligations  to  Mendel  and  his  disciples.6  If,  by 
skillful  selection  and  intelligent  breeding  methods  we  can  get  re- 
sults of  permanent  value;  if,  with  the  present  knowledge,  we  can 
make  real  progress  in  animal  breeding,  we  can  afford  to  wait  for 
the  more  definite  working  out  of  Mendel's  law,  with  the  assurance 
that  this  law  controls  the  mechanics  of  heredity  in  domestic  animals 
and  that  any  practical  application  of  it  to  animal  breeding  will  add 
to  our  store  of  useful  knowledge  and  to  the  efficiency  of  our  breeding 
methods. 

6  The  discovery  of  this  law  by  the  Austrian  monk,  Gregor  Mendel,  in  1865,  its  virtual 
disappearance  for  35  years  and  its  rediscovery  simultaneously  by  several  investigators 
working  independently,  form  one  of  the  romances  of  science.  Mendel's  papers  attracted 
very  little  attention  when  published,  owing,  no  doubt,  to  the  intense  interest  of  the 
world  in  the  researches  of  Darwin.  Mendel  died  in  1884  without  realizing  the  importance, 
to  humanity,  of  the  work  which  he  had  done. 


Essentials  of  Animal  Breeding.  17 

THE  ART  OF  BREEDING. 

SELECTION. 

Keeping  in  mind  the  principles  laid  down  in  the  foregoing  pages, 
it  is  clear  to  every  one  that  in  order  to  make  the  best  out  of  the 
hereditary  material  represented  in  one's  herd,  and  to  use  the  laws 
of  nature  to  the  best  advantage,  one  must  have  clearly  in  mind  a 
standard  which  he  sets  for  himself  as  the  ideal  toward  which  he 
must  work.  This  standard  must  be  definite  and  should  be  as  prac- 
tical and  simple  as  possible.  The  exercise  of  selection,  wisely  and 
judiciously  pursued,  offers  the  breeder  one  of  the  two  most  effective 
means  of  bending  to  his  own  purposes  the  operations  of  chance, 
which  otherwise  nature  will  use  to  his  confusion  and  undoing. 

We  have  made  the  statement  already  that  the  hereditary  material 
is  passed  down  from  generation  to  generation  without  change  ex- 
cept so  far  as  the  operation  of  the  laws  of  chance  may  have  affected 
the  process,  beginning  with  the  maturation  of  the  germ  cells.  It  is 
plain,  however,  that  constant  selection  of  a  good  type  will  increas- 
ingly intensify  the  properties  of  a  given  set  of  characteristics  (in 
other  words,  of  a  definite  type),  but  that  this  selection  must  be  pur- 
sued constantly  because  the  chromosomes  which  tend  to  produce  the 
less  desirable  types  continue  to  be  present,  although  in  decreasing 
numbers.  If  the  force  which  has  been  selecting  the  desirable 
chromosomes  is  removed,  then  the  undesirable  ones  may  once  more 
prevail.  In  other  words,  our  modern  breeds  of  farm  animals  are  an 
improvement  over  the  stock  from  which  they  sprang.  There  is, 
therefore,  a  constant  pull  backward  and  downward  against  which 
the  breeder  must  work  by  wise  selection  and  skillful  matings.  If 
this  intelligent  direction  by  human  skill  should  be  removed,  our 
animal  stock  would  rapidly  degenerate  to  the  level  of  the  types  of 
centuries  ago. 

Selection  should  be  -designed  to  correct  faults  in  the  parents,  and, 
as  a  rule,  the  male  is  depended  on  to  do  it.  A  few  concrete  cases  will 
illustrate.  If  the  females  have  a  tendency  to  be  too  leggy,  select  a 
male  that  is  compact  and  close  to  the  ground.  If  the  backs  are  not 
ideal,  select  a  male  with  an  exceptionally  strong  back.  If  the  sow's 
feet  are  not  the  best,  get  a  boar  that  is  unusually  strong  in  his  feet 
with  strong,  upright  pasterns.  We  might  multiply  these  illustra- 
tions indefinitely.  Therefore,  a  sire  should  be  a  better  individual 
than  the  females  with  which  he  is  to  be  mated ;  otherwise  the  stand- 
ard of  the  herd  or  flock  may  decline.  To  some  extent  a  breeder  may 
extend  these  principles  to  the  grandparents,  but  for  practical  work 
on  a  farm  that  is  producing  market  stock  it  is  commonly  unnecessary 
to  go  farther  back  than  the  sire  to  be  selected.  In  other  words,  don't 
3985°— 20 3 


18  Farmers'  Bulletin  1167. 

buy  a  poor  male  merely  because  some  one  tells  you  he  has  a  good 
pedigree. 

The  breeding  animals  selected  should  look  the  part.  Good  bone; 
deep,  broad  chests;  strong,  broad  backs;  and  fully  developed  bodies 
should  be  emphasized.  Especial  attention  should  be  paid  to  the  head, 
for  that  part  of  the  body  tells  many  a  story  which  otherwise  would 
be  overlooked.  Width  between  the  eyes,  full,  prominent  eyes  of 
pleasing  appearance,  broad  muzzles,  and  prominent  nostrils  indicate 


Hereford  Calf  Illustrating  Character. 

FIG.  10. — Compare  this  picture  with  those  of  other  bulls,  shown.  Each  one  shows 
strong  masculinity.  Each  one  has  an  individuality  aa  marked  and  striking  as  the 
individuality  shown  in  photographs  of  human  beings. 

points  of  value  both  to  the  breeder  and  the  feeder.  In  males,  strong 
evidence  of  masculinity  is  important.  The  evidence  of  the  masterful 
impressiveness  of  the  masculine  sex  is  often  apparent  in  very  young 
animals  and  may  be  taken  to  indicate  a  youngster  that  with  proper 
feed  and  care  will  grow  out  into  an  impressive  sire.  In  females  we 
look  for  femininity,  without  indications,  however,  of  weakness  of 
constitution.  Avoid  cows,  for  example,  with  heads  like  those  of 
steers.  These  points  make  up  in  total  what  breeders  call  "  charac- 


Essentials  of  Animal  Breeding.  19 

ter "  and  are  among  the  most  important  considerations  which  a 
breeder  must  bear  in  mind  in  building  up  his  herd  or  flock. 

Good  feed,  care,  and  attention  are  valuable  adjuncts  to  selection. 
Unless  feeding  permits  full  development  we  can  not  select  intelli- 
gently the  animals  which  have  received  and  can  transmit  the  charac- 
ters we  desire  to  perpetuate.  Starved  animals  which  never  have  had 
an  opportunity  to  demonstrate  their  capacity  to  produce  meat,  milk, 
wool,  or  other  valuable  commercial  products,  furnish  poor  material 
from  which  to  select  individuals  capable  of  maximum  and  most 
economical  production. 

One  must  use  these  rules  of  selection  with  judgment  and  common 
sense.  While  faults  undoubtedly  can  be  corrected  by  the  use  of 


Idolmere. 

FIG.  11. — Grand  champion  Aberdeen-Angus  bull  at  the  1919  International  Live  Stock 
Exposition.  One  of  the  greatest  bulls  of  the  breed  ever  seen  in  an  American  show 
ring.  An  exceptional  photograph  of  a  great  bull  showing  not  only  splendid  beef 
conformation  but  outstanding  breed  character  also.  Note  especially  the  strong 
character  as  shown  in  the  head  and  neck,  as  well  as  the  great  length  of  the  bull  and 
his  remarkable  smoothness. 

males  of  superior  individuality,  it  may  be  unwise  to  use  some  females 
for  breeding  even  market  stock  because  they  may  be  too  inferior  for 
even  this  purpose.  To  sell  them  and  substitute  better  individuals, 
either  high  grades  or  purebreds,  is  often  the  more  sensible  course 
and  the  more  profitable  in  the  end. 

Selection  alone,  however,  is  not  certain  to  result  in  steady  progress. 
Different  combinations  of  hereditary  elements  may  result  in  ap- 
parently the  same  characteristic.  In  practicing  selection  a  man  may 
introduce  at  any  time  the  blood  of  a  line  which  merely  looks  like 
that  of  his 'own  stock,  but  which  breeds  differently.  The  result  is 
the  undoing  of  past  progress,  the  next  generation  showing  the  vari- 


20  Farmers'  Bulletin  1167. 

ability  characteristic  of  the  second  generation  of  a  cross.  Only  by 
breeding  within  relatively  narrow  limits  can  one  be  reasonably  sure 
that  he  is  mating  animals  which  both  look  alike  and  have  the  same 
heredity. 

INBREEDING. 

Next  in  importance  to  selection  as  a  means  of  improvement  in 
breeding  animals,  the  most  effective  process  at  the  command  of  the 
breeder  is  the  judicious  mating  of  related  animals.  This  process  is 
known  as  inbreeding,  and  various  terms,  such  as  line  breeding,  close 
breeding,  and  incestuous  breeding,  have  been  used  to  define  varying 
degrees  of  intensity  of  the  process. 


Jersey  bull,  Pogis  99th  of  Hood  Farm  No.  94502. 

FIG.  12. — Animals  such  as  this  one  show  strong  evidence  of  breed  character,  mascu- 
linity, and  impressiveness. 

Inbreeding  is  one  of  the  most  discussed  subjects  in  the  whole 
field  of  genetics.  All  sorts  of  bad  results  are  attributed  to  it.  Lack 
of  vigor,  nonresistance  to  disease,  decline  in  size  and  fecundity,  and 
even  sterility  are  the  fate  of  inbred  animals,  in  the  minds  of  many 
people.  These  ideas  have  a  certain  basis  in  fact,  and  often  extend  to 
farmers,  who  sometimes  refuse  to  buy  males  which  have  inbred  pedi- 
grees. Breeds  and  families  which  have  been  intensely  inbred  for  sev- 
eral generations  develop  manifestations  of  constitutional  weakness 
which,  it  seems,  can  be  explained  only  on  the  grounds  of  their  close 
relationship.  Scientific  data  of  exact  and  elaborate  scope,  worked 
out  under  controlled  conditions,  are  not  abundant  on  this  point. 


Essentials  of  Animal  Breeding.  21 

We  have,  on  the  other  hand,  the  accepted  fact  that  progress  in 
animal  breeding  began  only  when  breeders  began  to  inbreed.  The 
work  of  Bakewell,  who  experimented  during  the  last  half  of  the 
eighteenth  century,  which  made  the  greatest  impression  was  the 
methods  he  used,  and  the  method  that  has  been  most  far-reaching 
in  its  results  was  that  he  mated  his  animals  with  first  regard  to  their 
individual  suitability  for  the  mating,  and  with  secondary  importance 
placed  on  their  relationship.  Since  the  time  of  Blakewell  every 
breeder  who  has  made  an  impress  of  permanent  importance  on  his 
breed  has  used  inbreeding  as  his  most  useful  working  tool. 


Purebred   Ayrshire   Bull,    Hobsland    Perfect    Piece    16933.      (Senior   Grand   Champion 
Ary shire  Bull.   National   Dairy   Show,   1914.) 

FIG.  13. — A  good  breeding  animal  impresses  the  observer  in  many  ways.  The  pose  of 
this  bull,  his  lines,  and  the  sweep  from  the  head  to  the  tip  of  the  tail  give  an 
unmistakable  impression  of  individuality,  power,  and  merit. 

When  we  mate  related  animals  we  are  bringing  together  animals 
with  a  more  nearly  uniform  character  in  their  hereditary  material 
than  when  we  mate  those  that  are  not  related.  We  are,  therefore, 
increasing  the  probability  that  the  offspring  will  be  like  the  parents. 
But  there  may  be  hidden  in  the  hereditary  material  the  factors  of 
an  undesirable  character.  In  other  words,  we  may  not  know  all 
that  we  should  know  about  the  ancestors.  Back  somewhere,  per- 
haps, was  a  bad  one  whose  traits  are  being  bred  out  by  selection  in 
each  successive  generation.  If  we  mate  two  related  animals  carry- 
ing this  defect,  we  greatly  increase  the  chance  of  perpetuating  it. 
Instead  of  having  an  even  chance  or  better  of  keeping  the  defect  under 


22 


Farmers9  Bulletin  H67. 


subjection  by  not  inbreeding,  we  double  the  chance  of  its  appearing 
when  we  do  inbreed.  It  seems  possible  to  inbreed  some  animals 
much  more  intensely  than  others,  and  certain  strains  of  breeds  in 
the  same  species  exhibit  similar  traits.  To  cite  specific  instances, 
cattle  which  have  a  special  susceptibility  to  tuberculosis,  horses  with 
a  tendency  to  certain  unsoundness,  such  as  roaring  or  spavin,  should 
not  be  inbred.  The  safe  rule,  therefore,  is  not  to  mate  closely  re- 
lated animals  which  have  the  same  defects,  either  themselves  or  in 
their  immediate  ancestors. 


Percheron  Stallion,  Dragon. 

FIG.  14. — Descendant  of  a  long  line  of  impressive  ancestors   and  himself  a   sire   of 

valuable  draft  horses. 

Inbreeding  should  be  practiced  only  by  the  most  skillful  breeders, 
and  by  them  only  when  they  have  definite  knowledge  of  the  an- 
cestry. Judiciously  used,  inbreeding  results  in  a  rapid  fixing  of 
type  and  enables  the  breeder  to  obtain  results  much  more  rapidly 
than  without  its  use.  It  is  like  any  other  high-powered  implement. 
Properly  used,  it  is  a  wonderful  adjunct  to  human  efforts;  in  the 
hands  of  the  ignorant  and  careless  it  is  a  source  of  danger. 


Essentials  of  Animal  Breeding. 


23 


The  purchaser  of  inbred  males,  however,  need  have  no  fear  of  using 
them  if  they  are  creditable  representatives  of  the  breed.  As  a  matter 
of  fact,  he  should  prefer  inbred  males  to  others,  especially  if  they  are 
not  related  to  his  females,  because  they  are  more  nearly  alike  in  their 
hereditary  material,  and  for  that  reason  more  likely  to  reproduce 
themselves  with  uniformity.  They  are  usually  sold  under  a  guaran- 
ty that  they  are  breeders  (or  they  should  be  so  sold),  and  if  they  do 
not  breed,  any  reputable  breeder  will  replace  them.  It  is  a  general 
rule  that  inbred  animals,  when  mated  to  unrelated  ones,  even  though 


Clydesdale  Stallion,  Fyvie  Baron. 

FIG.  15. — Note  intelligent  head  and  strong,  crested  neck,  as  well  as  evidence  of  vigor- 
ous constitution,  indicated  by  depth  of  body. 

the  latter  themselves  are  inbred,  produce  offspring  larger  and  more 
vigorous  than  either  parent.  From  every  standpoint,  therefore,  an 
inbred  sire  should  be  desirable  to  use  in  a  farmer's  herd,  provided  the 
animal  is  a  good  individual.  The  farmer  should  make  certain  of 
this  fact.  Then  he  should  ascertain  that  the  strain  itself  is  vigorous, 
and  finally  he  should  have  a  guaranty  that  the  animal  bought  will 
prove  to  be  a  breeder.  If  these  conditions  are  met,  the  farmer  will 
find  inbred  males  much  more  impressive  and  will  have  a  much  more 
rapid  return  in  improving  his  stock  than  if  he  had  used  males  which 
were  not  inbred. 


24  Farmers'  Bulletin  1167. 

Whether  a  breeder  should  or  should  not  inbreed  his  stock  is  a 
matter  which  he  must  settle  for  himself.  The  successful  use  of  in- 
breeding is  one  of  the  best  tests  of  a  breeder's  skill,  and  no  man  should 
inbreed  unless  he  is  confident  that  he  possesses  the  requisite  skill  to 
make  such  a  step  successful.  Generally  speaking,  the  inbreeding  of 
market  stock  is  unwise;  but  the  use  of  inbred  males  on  the  females 
of  such  a  stock  may  be  of  the  highest  value,  provided  the  breeding 
establishment  which  produced  the  males  has  not  been  injured  by 
inbreeding.  Such  a  fact  can  be  readily  ascertained. 

Inbreeding  fixes  characters  which  can  be  fixed,  but  one  of  its  most 
valuable  consequences  is  bringing  clearly  to  light  the  relative  merits 
of  different  strains  in  such  characters  as  fecundity,  resistance  to 
disease,  and  the  like,  which  are  affected  so  much  by  factors  other  than 
heredity  that  they  can  not  be  fixed  in  individuals.  In  these  cases 
progress  is  more  likely  to  result  from  selection  of  strains  than  from 
the  selection  of  individuals. 

A  real  danger  from  inbreeding  is  not  to  be  urged  against  the 
practice  itself,  but  against  the  peculiar  infatuation  which  breeders 
acquire  for  certain  bloodlines.  Once  let  a  given  line  of  breeding 
demonstrate  its  excellence  for  the  production  of  a  certain  valuable 
type,  and  every  progressive  breeder  strives  to  acquire  some  of  this 
valuable  blood.  The  strain  soon  becomes  "  fashionable."  From 
this  stage  to  breeding  for  the  pedigree  rather  than  for  the  animal 
is  an  easy  step  which  is  taken  much  too  often.  The  corrective  for 
such  methods  is  the  show  ring,  with  competent  and  fearless  judges 
in  authority. 

OUTCROSSING. 

Quite  the  converse  of  inbreeding  is  the  practice  of  outbreeding  or 
outcrossing.  Even  in  plants  which  are  usually  self-fertilized,  nature 
has  provided  for  an  occasional  outcross  that  materially  increases  the 
vigor,  stamina,  and  general  well-being  of  the  stock.  In  animals 
which  have  been  intensely  inbred,  outcrossing  has  interesting  and 
important  results.  Mating  to  stock  which  has  not  been  inbred 
results  in  increases  in  size  and  vigor.  A  similar  result  also  follows 
the  mating  of  two  strains,  both  of  which  have  been  inbred,  but  which 
are  not  closely  related  to  each  other. 

PURE   BREEDING. 

Step  by  step  we  climb  the  ladder  of  the  art  of  breeding  until  we 
finally  reach  the  top  in  the  breeding  of  purebreds,  the  most  fascinat- 
ing, the  most  inspiring,  and  the  most  remunerative  branch  of  animal 
breeding  when  successfully  followed ;  the  most  difficult  and  the  most 
disappointing  when  not  successful.  The  successful  breeder  of  this 
class  of  animal  is  far  more  than  a  business  man  or  a  farmer.  He  is 
an  artist,  and  the  artistic  appeal  is  first  in  importance  to  him. 


Essentials  of  Animal  Breeding.  25 

The  basis  of  pure  breeding  in  the  United  States,  except  in  the  case 
of  poultry  and  pet  stock,  is  pedigree  registration.  Animals  must  be 
not  only  purebred,  but  they  must  be  registered  in  the  book  of  record 
established  for  the  breed. 

Standards  in  pure  breeding  are  more  exacting  and  more  compli- 
cated than  in  breeding  solely  for  the  production  of  meat,  wool,  milk, 
or  eggs,  but  they  should  be  practical,  because  the  proof  of  the  prac- 
tical value  of  a  breeder's  work  is  the  demand  which  is  sustained  in 
the  long  run  for  his  breeding  animals.  The  surplus  of  the  registered 
purebred  establishments  goes  to  improve  the  native  and  unregistered 
grade  herds  and  into  purebred  herds  of  less  merit.  A  high  stand- 
ard is  therefore  absolutely  essential  to  maintain  quality,  average 
excellence,  and  the  reputation  of  the  herd.  Practical  ideals  must  have 
quite  as  much  weight  as  purely  commercial  considerations  in  the 
determination  of  the  standards. 

A  breeder's  success  depends  to  a  very  large  extent  on  his  ability 
as  a  qualified  judge  of  animals,  on  his  knowledge  of  the  pedigrees 
of  his  animals,  and  on  his  acquaintance  with  the  characteristics  of 
the  ancestors  of  those  animals.  The  breeder's  ability  as  a  judge 
must  be  based  on  an  instinctive  gift  to  recognize  animal  types  and 
carry  them  clearly  in  mind.  This  is  of  even  more  importance  than 
a  knowledge  of  pedigrees,  because  a  knowledge  of  pedigrees  is  of 
practical  value  only  as  it  gives  its  possessor  an  acquaintance  with 
the  individuality  and  type  of  the  ancestors  in  the  pedigrees,  which 
he  may  use  in  making  effective  matings  and  thus  perfecting  the 
type  of  his  animals.  One  of  our  most  eminent  breeders  of  hogs 
once  made  the  statement,  "I  breed  my  hogs  in  the  barnyard,  with 
the  animals  before  me,  not  in  my  parlor  with  their  pedigrees  before 
me."  That  homely  statement  carries  a  truth  which  every  ambi- 
tious young  breeder  should  follow.  Before  deciding  to  make  a 
certain  mating,  the  man  who  made  this  statement  is  said  to  spend 
hours  studying  his  breeding  animals,  going  over  their  character- 
istics, and  especially  recalling  to  mind  the  characteristics  of  their 
parents,  grandparents,  and  more  remote  ancestors.  If  this  review 
is  satisfactory,  the  mating  is  made ;  if  not,  some  other  is  tried. 

To  sum  up,  knowledge  of  a  pedigree  must  not  stop  with  the 
routine  knowledge  of  the  names  of  the  animals  which  compose  it. 
The  breeder  must  know  also  the  characteristics  of  these  animals,  as 
far  back  as  possible,  their  weaknesses  as  well  as  their  strong  points. 
When  he  possesses  this  information  the  breeder  can  more  intelli- 
gently mate  individuals  and  blend  bloodlines.  He  has  then  a  prac- 
tical working  knowledge  of  pedigrees.  The  study  of  pedigrees, 
therefore,  based  on  a  knowledge  of  the  characteristics  of  the  ani- 
mals composing  them,  is  indispensable  to  the  man  who  would  excel 
as  a  constructive  breeder. 


26 


Farmers'  Bulletin  1167. 

THE  VALUE  OF  A  PEDIGREE. 


No  one  breeds  animals  without  dealing  with  pedigrees.  The 
common  phrase  "  pedigree  stock,"  as  a  synonym  of  "  well-bred  "  or 
"  purebred "  in  describing  livestock,  is  a  misnomer.  All  plants, 
all  animals,  all  people  have  pedigrees,  but  all  information  about 
these  pedigrees  is  not  available.  Pedigrees  become  known  because 
of  merit  in  some  individual  which  stands  out  above  his  fellows. 


The  Sire  of  a  Grand  Champion. 

FIG.  16. — To  achieve  the  highest  results  in  livestock  production  pure  blood  is  most 
likely  to  result  satisfactorily.  Illustration  shows  the  Shorthorn  bull,  Lavender 
Sultan,  sire  of  the  three  steers  shown  in  figure  18.  This  bull  is  a  remarkably 
impressive  sire  with  wonderful  thickness  of  flesh.  Note  how  his  thick  flesh  is 
transmitted  to  his  sons.  Compare  this  picture  with  figures  17  and  18. 

His  progeny  are  watched,  and  if  they  have  merit  above  the  average 
they  are  "saved  for  breeding  purposes,"  and  by  and  by  we  have 
a  line  of  known  descent  and  ultimately  perhaps  a  pedigree  of  dis- 
tinction and  formidable  appearance.  They  are  written  into  genealo- 
gies, herdbooks,  flock  books,  and  studbooks,  and  the  inheritance  of 
decades  and  even  of  centuries  becomes  in  time  a  matter  of  written 
record. 

The  proof  of  the  value  of  the  pedigree  itself  is  the  worth  of  the 
animals  it  produces.     The  value  of  animals  with  certain  pedigrees 


Essentials  of  Animal  Breeding. 


27 


depends  upon  their  ability  to  produce  desirable  types  with  greater 
excellence  and  uniformity  than  animals  with  other  pedigrees  or 


The  Dam  of  a  Grand  Champion. 

FIG.  17. — Merry  Sempstress,  dam  of  Merry  Monarch,  the  grand  champion  steer  at  the 
International  Live  Stock  Exposition  in  1919.  Note  not  only  her  beef  conformation 
but  her  good  feeding  qualities,  clearly  indicated  in  a  head  which  is  almost  an  ideal 
feeder's  type,  as  well  as  an  ideal  breed  type.  She  shows  excellent  indications  of 
real  feminine  character. 


A  Triumph  of  Breeding  and  Feeding. 

FIG.  18. — Merry  Monarch  (right),  grand  champion  steer  at  the  1918  International  Live 
Stock  Exposition,  and  two  other  prize-winning  sons  of  Lavender  Sultan.  Compare 
with  figures  16  and  17. 

with  no  known  pedigrees  whatever.  The  power  of  the  animal  with  a 
known  pedigree  to  reproduce  its  type  has  been  intensified  by  selection. 
Therefore,  if  the  matings  which  have  been  made  in  constructing  the 


28 


Farmers1  Bulletin  1167. 


pedigree  have  not  been  directed  by  a  high  order  of  skillful  selection, 
the  animal  may  have  intensified  powers  of  producing  an  undesirable 
type,  and  may  be  what  is  commonly  designated  a  "  scrub  purebred.'' 
The  purchase  of  an  animal  or  its  use  for  breeding  purposes  solely 
on  account  of  its  pedigree  is  a  dangerous  matter  and  may  result  in 
much  more  harm  than  good. 

What  is  the  most  important  part  of  the  pedigree?  Usually  only 
the  ancestors  which  are  "  close  up  "  are  those  which  are  of  practical 
importance  in  determining  the  identity  of  the  individual.  Assuming 
that  Mendel's  law  governs  animal  inheritance,  we  may  occasionally 


The  Main  Points  of  a  Pedigree. 

FIG.  19. — A  graphic  representation  of  the  relative  importance  of  ancestors  in  the  first 
four  generations.  Families  in  livestock  often  trace  their  foundation  to  a  single  animal 
which  may  not  be  reached  within  ten  generations.  It  is  quite  as  important  to  know 
what  sort  of  animals  make  up  the  later  matings  as  it  is  to  know  to  what  family  the 
animal  belongs.  The  proof  of  the  value  of  a  pedigree  is  the  worth  of  the  animals  it 
produces. 

expect  to  find  an  off-type  occurring,  but  by  the  repeated  culling  out 
of  such  types  the  frequency  of  their  occurrence  is  being  constantly 
reduced.  Therefore,  if  we  are  sure  of  the  parents  and  know  what  is 
in  the  first  three  or  four  generations  of  an  animal's  pedigree,  we 
know  the  most  important  facts  about  that  pedigree.  In  generations 
beyond  the  third  or  fourth  the  influence  of  any  ancestor  is  so  slight 
that  for  practical  purposes  it  may  be  ignored. 

In  a  four-generation  pedigree  there  are  30  ancestors,  all  of  which 
may  be  different  individuals.  Usually  in  pedigrees  of  most  purebred 
herds  there  are  fewer  than  30  separate  individuals,  depending  on  the 
amount  of  inbreeding  in  the  pedigree.  The  chart  (fig.  19)  shows  this 


Essentials  of  Animal  Breeding.. 


29 


fact  graphically.  Suppose  there  is  no  inbreeding  in  a  four-genera- 
tion pedigree,  the  chance  that  one  of  the  animals  in  the  fourth  gen- 
eration will  dominate  the  pedigree  above  all  others  is  very  small 
indeed.,  The  chart  thus  shows  graphically  the  relative  importance 


Grading  Up  With  Sheep. 

FIG.  20. — The  ewe  at  the  left  is  a  Mississippi  Piney-Woods  native.  The  lamb  is  her 
produce  by  a  purebred  Shropshire  buck.  At  four  months  of  age  the  lamb  outweighed 
not  only  her  mother  but  any  other  ewe  in  the  flock.  Note  the  absence  of  wool  on 
the  belly  of  the  ewe  and  the  good,  thick,  uniform  fleece  of  the  lamb. 

of  the  respective  ancestors  for  four  generations.  Each  figure  in  the 
chart  is  just  half  the  size  of  the  one  in  the  generation  preceding,  and 
this  conforms  fairly  well  to  the  standard  formula  of  inheritance. 


Farmers'  Bulletin  1167. 


The  chance  of  grandparents'  dominating  the  inheritance  of  the 
mating  can  not  be  more,  and  is  undoubtedly  much  less,  than  1  in 


Grading  Up  With  Dairy  Cattle. 

FIG.  21. — The  result  cf  15  years'  consistent  work  with  purebred  bulls, 
grade  Jersey  herd  bred  up  from  a  native  foundation. 


A  Mississippi 


6;  the  chance  of  a  great-grandparent  is  less  than  1  in  14;  and  the 
chance   of   a   great-great-grandparent    (fourth   generation)    is   less 

than  1  in  30,  provided  no  in- 
breeding occurs.  In  a  pedigree 
covering  10  generations  (which 
can  easily  be  run  out  with  almost 
any  of  our  well-established  breeds 
of  domestic  animals)  there  are 
2,046  ancestors,  more  than  half 
of  which  are  in  the  tenth  genera- 

k;   J^:  tion.     Yet   cattle   are   sometimes 

"^ilBto      **'•••  s°ld    at    a    premium    because    a 

certain  cow  appears  in  the 
pedigree  as  far  back  as  the  tenth 
generation  or  even  further,  re- 
gardless of  the  merit  of  animals 
much  further  down  in  the  pedi- 
gree. Or  a  pedigree  may  be 
classed  as  unfashionable  and  the 
animal  carrying  it  may  be  dis- 
criminated against,  regardless  of 

Plymouth  Rock  males.  its  individual  excellence,  because 

some  unpopular  animal  may  have  appeared  in  an  extremely  remote 
generation. 


Value  of  Pure  Blood. 

FIG.  22. — In  1915  the  Bureau  of  Animal 
Industry  purchased  on  the  Washington 
(D.  C.)  market  a  flock  of  mongrel  hens. 
These  hens  were  mated  to  standardbred 
males  to  show  how  mongrel  flocks  could 
be  improved  by  grading  up.  This  illus- 
tration shows  a  mongrel  hen,  and  the 


Essentials  of  Animal  Breeding. 


31 


LIVESTOCK  IMPROVEMENT. 

GRADING  UP. 

The  process  of  improving  native  stock  by  breeding  the  females  to 
purebred  males  is  termed  grading  up.     The  first  cross  is  usually  a 


Value  of  Pure  Blood. 

FIG.  23. — Barred  Plymouth  Rock  male  used 
for  the  first  cross  on  mongrel  hens  such 
as  the  one  shown  in  the  preceding 
illustration. 


Value  of  Pure  Blood. 

FIG.  24. — First-cross  pullet  of  mongrel  hen 
shown  in  figure  22  and  sired  by  male 
shown  in  figure  23. 


Value  of  Pure  Blood. 

FIG.  25. — Second-cross  pullet.  Size,  con- 
formation, and  color  of  pattern  have 
been  greatly  improved. 


Value  of  Pure  Blood. 

FIG.  26. — Third-cross  pullet.  Fanciers 
who  did  not  know  how  she  was  bred 
would  call  this  pullet  a  good  representa- 
tion of  the  breed. 


very   noticeable   improvement   over   the   native   stock.     When    the 
females  of  this  mating  are  bred  to  a  male  of  the  same  breed,  greater 


32 


Farmers'  Bulletin  1167. 


fixity  of  type  appears.  Continued  use  of  males  of  the  same  breed 
results,  in  a  comparatively  short  time,  in  animals  which  are  practi- 
cally purebred,  although  not  eligible  to  registration  and  therefore  not 
salable  as  purebreds. 

In  grading  up,  consistent  methods  should  be  used  and  males  of  the 
same  breed  used,  cross  after  cross;  otherwise  the  stock  will  be  mon- 
grelized  instead  of  improved.  Males  should  also  be  better  indi- 
viduals in  all  respects  than  the  females  with  which  they  are  mated, 
in  order  that  each  successive  cross  may  be  an  improvement  over  the 
ones  which  went  before  it. 


Uniformity  Quickly  Obtained  by  Use  of  Purebred  Males. 

FIG.  27. — Kids  at  the  Experiment  Farm  of  the  Bureau  of  Animal  Industry,  Beltsville, 
Md.,  by  purebred  Saanen  bucks  on  foundation  of  native  does. 

CROSSBREEDING. 

Crossbreeding  is  the  mating  of  purebred  animals  of  different  breeds 
of  the  same  species.  Crossbred  animals  are  usually  larger  and  more 
vigorous  than  either  parent.  Their  hereditary  material,  however, 
is  so  complex  that  there  is  no  certainty  as  to  what  results  will  come 
from  mating  them.  Except  to  produce  market  animals,  crossbreed- 
ing should  be  used  only  by  the  highly  skilled  breeder,  and  it  is  not 
practicable  in  his  case  unless  he  has  an  opportunity  to  place  the 
progeny  on  the  market  for  breeding  purposes.  American  practice  in 
livestock  breeding  does  not  encourage  the  development  of  new  breeds 
except  in  the  case  of  poultry  and  pet  stock.  Therefore  the  practical 
man,  as  a  rule,  will  leave  this  matter  to  the  experimentalists. 


Essentials  of  Animal  Breeding.  33 

SOME  INCORRECT  IDEAS  OF  HEREDITY. 

From  the  earliest  beginnings  of  rational  mental  processes  human 
beings  have  asked  the  question  "  Why  ?  "  Failing  to  receive  an 
answer  concerning  things  which  they  could  not  understand  they 
have  theorized  and  developed  explanations  as  a  result  of  such  theories 
which  often  have  not  had  any  basis  in  fact.  From  the  time  when  the 
simple  shepherds  of  Asia  watched  their  flocks  beneath  the  stars  and 
wondered  at  the  mysteries  of  nature  around,  above,  and  beneath 


A  Fast-Disappearing  Type. 

FIG.  28. — Native  Piney-Woods  sow.  Note  the  wattles.  These  sows  are  prolific,  good 
milkers,  and  good  mothers.  In  other  respects  they  have  nothing  to  commend  them. 
Purebred  sows  are  just  as  prolific,  just  as  good  milkers  and  mothers,  and  make  pork 
far  more  rapidly  and  more  economically. 

them,  man  has  marveled  at  the  mysteries  of  heredity.  In  some  form 
or  other  many  of  these  meditations  have  persisted  until  modern 
times  as  beliefs  for  which  no  unassailable  proof  has  ever  been  pre- 
sented. 

TELEGONY. 

These  beliefs  are  sometimes  intensified  by  an  apparent  confirmation 
from  scientific  sources.  Possibly  the  most  outstanding  instance  of 
this  kind  is  the  famous  case  of  Lord  Morton's  mare,  which  in  the 
opinion  of  the  great  Charles  Darwin  confirmed  the  theory  of  telegony. 


34  Farmers'  Bulletin  1167. 

This  theory  was  that  the  first  male  to  impregnate  a  female  perma- 
nently endowed  the  female  with  his  characters,  so  that  subsequently 
she  would  always  exhibit  them  in  her  progeny.  If  this  male  was  of 
another  breed  the  female  became  a  crossbred  by  means  of  this  first 
impregnation.  The  Lord  Morton  mare  was  a  Thoroughbred;  she 
was  mated  with  a  quagga  and  produced  a  hybrid  foal.  She  was 
then  mated  to  a  Thoroughbred  stallion  and  produced  a  foal  with 
stripes.  In  spite  of  the  fact  that  Darwin  knew  that  frequently  horses 
had  both  shoulder  stripes  and  leg  stripes,  and  that  mules  with  leg 
stripes  were  known  to  occur,  he  coupled  this  Morton  case  with  the 
erroneous  beliefs  of  dog  breeders  and  gave  the  theory  in  question 
the  powerful  support  of  his  authority.  The  theory  has  been  com- 
pletely disproved  by  Ewart,  who  has  clearly  shown  it  to  have  been 


Purebred  Poland  China  sow. 
FIG.  29. — Contrast  this  picture  with  the  photograph  of  the  Piney-Woods  sow. 

a  manifestation  of  inheritance.  Horses,  asses,  and  other  equine  stock 
have  a  common  origin.  With  our  present  knowledge  of  Mendel's  law, 
which  was  unknown  to  Darwin,  we  can  understand  much  more  readily 
that  the  appearance  of  stripes  in  horse  stock  is  more  likely  due  to  the 
unexpected  appearance  of  a  recessive  character  than  to  any  residu- 
ary effect  of  any  impregnation  on  the  chromosomes  of  the  female 
germ  cells.  Such  a  theory  is  utterly  impossible  if  we  accept  the 
known  facts  regarding  the  chromosomes  and  their  behavior.7 

Crosses  most  readily  demonstrate  the  operations  of  Mendelism, 
and  the  more  violent  the  cross  the  more  astonishing  are  the  results. 
It  often  happens  that  the  cross  of  ass  and  mare  brings  to  the  surface 
characters  common  to  the  horse  ancestors  of  the  distant  past.  An- 
other interesting  case  is  seen  in  crossing  certain  breeds  of  hogs,  re- 

7  See  pages  5-8. 


Essentials  of  Animal  Breeding. 


35 


suiting  in  young  which  have  the  longitudinal  stripes  characteristic 
of  the  young  wild  boar. 

MATERNAL  IMPRESSIONS. 

A  famous  ancient  classic  is  the  bargain  which  Jacob  made  with 
his  father-in-law  Laban,  and  since  its  historic  consummation  some 
breeders  of  cattle  have  believed  that  the  presence  of  objects  of  strik- 
ing form  or  color  before  the  eyes  of  the  female  at  the  time  of  con- 
ception have  an  influence  on  the  characteristics  of  the  progeny.  So 
far  as  the  Biblical  case  is  concerned,  the  writer's  impression  is  that 
Laban  was  not  so  skilled  in  the  animal  husbandry  of  his  day  as  was 


Purebred  Duroc-Jersey  boar. 

FIG.  30. — Quick  results  can  be  obtained  by  using  such,  males  on  native  sows,  or  an 
investment  may  be  made  in  one  or  two  purebred  sows,  from  which  an  entire  herd  of 
purebreds  is  soon  at  hand. 

his  crafty  son-in-law,  and  judging  by  Avhat  we  know  to-day  of  the 
livestock  of  Palestine,  it  would  have  been  far  more  remarkable  if  a 
large  proportion  of  the  calves  had  not  been  speckled  and  spotted.8 
A  much  more  modern  case  is  that  of  McCombie,  of  Tilly  four,  one  of 
the  early  Scotch  improvers  of  Aberdeen- Angus  cattle,  who  is  reported 
to  have  believed  that  he  could  increase  the  proportion  of  black  cattle 
in  his  herd  by  having  his  barns  and  fences  painted  black.  The  red 
color  was  comparatively  common  among  Angus  cattle  a  hundred 
years  ago,  and  breeders  were  constantly  culling  out  that  color.  From 
what  we  now  .know  of  the  action  of  the  chromosomes,  it  was  selection 
and  not  the  color  of  McCombie's  barns  that  made  the  Angus  cattle 
"black  and  all  black."  Even  to-day  an  occasional  red  Angus  calf 
appears,  as  we  would  expect  to  happen  according  to  the  Mendelian 

8  See  Genesis  xxx  :  25-43. 


36  Farmers'  Bulletin  1167. 

law  of  inheritance.  If  the  color  before  the  cow's  eyes  at  the  time  of 
service  had  anything  to  do  with  the  color  of  the  calf,  the  red  barns 
of  the  Corn  Belt  would  long  since  have  had  an  astonishing  effect  on 
our  American  Angus  cattle. 

Even  monstrosities  in  animals  are  probably  the  appearance  of 
some  long-submerged  character,  brought  up  out  of  the.  stream  of 
inheritance  by  some  peculiar  combination  of  the  hereditary  ele- 
ments. Certain  animals  and  certain  strains  produce  monstrosities 
more  often  than  others.  Many  of  these  can  be  brought  out  readily 
by  intensive  inbreeding. 

The  pregnant  mother,  whether  of  the  human  or  of  the  animal 
family,  should  be  an  object  of  the  utmost  solicitude  and  should 
receive  the  most  thoughtful,  tender  care.  She  is  engaged  in  a  double 
duty.  The  development  of  the  young  creature  in  her  body  taxes 


How  Good  Breeding  Affects  Size. 

FIG.  31. — The  large  animal  is  a  yearling  Aberdeen- Angus  steer.  The  smaller  one  is  a 
three-year-old  Piney-Woods  steer.  The  difference  between  the  two  is  due  almost 
entirely  to  difference  in  breeding. 

both  bodily  strength  and  nervous  organization.  We  must  not  for- 
get, however,  that  there  is  no  direct  connection  of  circulation  or 
nervous  system  between  the  mother  and  the  fetus.  Therefore  the 
fetus  can  not  be  affected  by  what  the  mother  sees  or  hears.  Acci- 
dents to  the  mother,  however,  such  as  sudden  strains,  falls,  etc., 
may  have  effects  resulting  in  the  serious  injury  or  death  of  the 
young.  These,  again,  are  not  due  to  heredity,  no  matter  what  the 
effect  on  the  young  may  be. 

CONCLUSIONS. 

The  writer  does  not  presume  by  any  means  to  believe  that  his 
effort  will  succeed  in  removing  completely  from  the  minds  of  men 
their  fallacious  beliefs  concerning  animal  inheritance,  but  he  does 
hope  that  he  may  have  some  influence  in  causing  those  who  breed 
animals  to  look  more  to  nature  herself  and  to  tlie  operation  of  her 


Essentials  of  Animal  Breeding. 


37 


laws  for  the  explanation  of  the  'facts  which  they  observe  and  not 
try  to  explain  them  as  due  to  supernatural  causes.  To  summarize 
very  briefly,  let  us  bear  in  mind  the  following  fundamental  facts  : 

1.  All  animal  forms  on  the  earth  have  developed  gradually  from 
lower  forms  by  very  slow  changes.     This  is  the  process  known  as 
evolution. 

2.  The  young  animal  starts  on  its  career  when  two  bits  of  heredi- 
tary material  (germ  plasm)  unite,  one  from  the  female  (the  egg) 
and  the  other  from  the  male  (the  sperm).     When  the  union  is  com- 
plete, the  sex,  identity,  and  individuality  of  the  animal  are  settled. 
Chance  plays  a  most  important  part  in  determining  these  factors. 

3.  From  now  on  the  fate  of  the  animal  depends  on  its  nourish- 
ment and  environment. 


Why  Cloud  a  Boy's  Dreams  With  This  Kind  of  Stock? 

FIG.  32. — Give  the  youngsters  well-bred  pigs,  calves,  sheep,  and  chickens,  and  they  will 
be  much  more  likely  to  stay  on  the  farm  and  become  producers  of  useful,  profitable 
animals  to  the  advantage  of  their  own  pocketbooks  and  the  wealth  of  the  Nation. 

4.  The  breeder  can  do  much  to  bend  the  operations  of  the  laws 
of  chance  to  his  own  ends  by  careful  selection  of  breeding  stock. 
u  Breed  the  best  to  the  best." 

5.  Next  to  selection  the  best  means  at  the  command  of  the  breeder 
to  fix  type  in  his  animals  is  inbreeding.     It  is  a  powerful  tool,  but 
a  dangerous  one  in  unskillful  hands.     Inbred  sires  are  more  im- 
pressive as  a  rule  than  sires  which  are  not  inbred. 

6.  Nature   does  not   work  lawlessly.     Occurrences  attributed   to 
supernatural  means  can  be  more  rationally  explained  as  a  manifesta- 
tion of  some  operation  of  a  law  of  heredity. 

If  a  breeder  has  a  clear  conception  of  these  facts,  he  can  usually 
explain  by  one  or  the  other  nearly  every  occurrence  which  he  may 
observe.  The  clearer  he  thinks  on  these  subjects  the  more  successful 
he  will  be  as  a  breeder. 


38  Farmers'  Bulletin  1167. 

PUBLICATIONS  OF  UNITED  STATES  DEPARTMENT  OF  AGRICUL- 
TURE RELATING  TO  BREEDING  AND  RAISING  LIVESTOCK. 

AVAILABLE  FOR  FREE  DISTRIBUTION  BY  THE  DEPARTMENT. 

Breeds  of  Sheep  for  the  Farm.     (Farmers'  Bulletin  576.) 

Breeds  of  Beef  Cattle.     (Farmers'  Bulletin  612.) 

Breeds  of  Draft  Horses.     (Farmers'  Bulletin  619.) 

Colts:  Breaking  and  Training.     (Farmers'  Bulletin  667.) 

Breeds  of  Swine.     (Farmers'  Bulletin  765.) 

Dairy  Calves  and  Young  Dairy  Stock.     (Farmers'  Bulletin  777.) 

How  to  Select  a  Sound  Horse.     (Farmers'  Bulletin  779.) 

Standard  Varieties  of  Chickens:  I.  The  American  Class.     (Farmers'  Bulletin 

806.) 

Farm  Sheep  Raising  for  Beginners.     (Farmers'  Bulletin  840.) 
Breeds  of  Dairy  Cattle.     (Farmers'  Bulletin  893.) 
Standard  Varieties  of  Chickens  :   II.  The  Mediterranean  and  Continental  Classes. 

(Farmers'  Bulletin  898.) 

Breeds  of  Light  Horses.     (Farmers'  Bulletin  952.) 
Standard  Varieties  of  Chickens :  III.  The  Asiatic,  English,  and  French  Classes. 

(Farmers  Bulletin  1052.) 

PUBLICATIONS    RELATING   TO    LIVESTOCK    IMPROVEMENT. 

Castration  of  Pigs.     (Farmers'  Bulletin  780.) 

Production  of  Baby  Beef.     (Farmers'  Bulletin  811.) 

Livestock  Classification  at  County  Fairs.     (Farmers'  Bulletin  822.) 

Swine  Management.     (Farmers'  Bulletin  874.) 

Dehorning  and  Castration  of  Cattle.     (Farmers'  Bulletin  949.) 

Cooperative  Bull  Associations.     (Farmers'  Bulletin  993.) 

Judging  Beef  Cattle.     (Farmers'  Bulletin  1068.) 

Growing  Beef  on  the  Farm.     (Farmers'  Bulletin  1073.) 

Castrating  and  Docking  Lambs.     (Farmers'  Bulletin  1134.) 

"Better  Sires — Better  Stock"  booklet. 

"  Which  Way  Is  Your  Livestock  Going?  "  poster. 

"  Purebred  Sires  and  Herd  Improvement "  poster. 


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